Muffler



Filed Aug.' 31, 1932 Il /w 1 ATTORNEY Patented Apr. 3, 1934 AUNITI-:D STATES PATENT OFFICE MUFFLEB Michigan Applicatin August 31, 1932, serial No. 631,188

1 Claim.

This invention relates to muillers.

The principal objects of the invention are novel muller combinations employing parts which provide resonance chambers in the muillers, the mufflers being so constructed as to providean extremely low back pressure, consistent with effective silencing.

Still further objects will be observed upon reference to the following detailed description of an embodiment of the invention, this embodiment beingshown in the appended drawing.

The figure shows in sectional elevation one form of mufller.

The mulller of the figure includes an outer shell 30, an intermediate shell 31 and an inner shell 32. In the right or inlet end of the shell 30 there is disposed an inlet head 34 having a portion drawn out of the muiiler to provide an inlet 36. In the outlet end of the muiller there is disposed an outlet head 35 having an outlet portion 37.

The intermediate shell 31,. connected to the outlet head 35, does not extend all the way to the inlet head 34 but is spaced therefrom a slight distance and is connected at the inlet end to the outer shell 30 by'a plate 38 as indicated. The inner shell 32, also connected to the outlet head 35, has its right end spaced from the inlet head 34 a considerable distance, this end of the inner shell being closed by a plug 39.

The intermediate shell is provided with a plurality of relatively large holes 40 near the inlet end of the muler, and is also provided with a second series of relatively large holes 41 closely adjacent the outlet he 35. A baiile plate 42 disposed intermediate the holes 40 and 41 connects the intermediate shell to the outer shell v and forms resonance chambers R3 in the space between these shells, it being observed that as many of these baflles may be provided as desired, the embodiment shown having but one of these baffles.

The inner shell is connected to the intermediate shell 31 by a plurality of bailles 45 which form sound wave 'attenuating chambers R4 in the space between the inner and intermediate shells, there being as'many of these bailles as desired to form as many chambers R4 as desired. That portion of the inner shell between its plugged end and the righthand one of the baffles 45 is covered with a large number of small holes 46. The remainder of the inner shell, that is to say, that portion thereof between the righthand baflle..45 and the outlet 37 is covered with a large number of closely spaced and outwardly extruded minute perforations 47, preferably slightly smaller than the perforations 46.

The operation and functions of the construction are as follows: Exhaust gases enter the muffler through inlet 36 and pass into the expansion chamber` C provided in the intermediate shell 31 between the baille 45 and the inlet -end of the muiller. The gases expand freely in this expansion Vchamber and a portion of them pass into the outer resonance chamber R3 through the holes 40. Another portion of the gases enters the inner shell through the small holes 46, from where they pass unobstructed through the outlet 37, this much ofthe muiiier being in the nature of a through muiller. A portion of the gases that enter the irmer shell escapes through perforations 47 into the inner chambers R4 between bailles 45. A still further portion of the gases escape from the lefthand inner chamber R4 to the lefthand outer resonance chamber R3 through the holes 41 of the intermediate shell.

The construction of the figure, while not exactly a through jmuiller, there being at least one interruption to the unobstructed flow of exhaust gases from inlet 36 to outlet 37, nevertheless is of the low back pressure type, and is an effective silent muiller. The expansion chamber C in the inlet end of the intermediate shell 31, prevents an undue rise in the back pressure, as will readily be seen.

Now having described one embodiment of the invention, reference will be had to the following claim which determines the scope of the invention, it being observed at this time that the invention is not to be limited to the specic details and proportions heretofore shown and described.

What we claim is:

In a silencer having an inlet head at one end and an outlet head at the other, the combination of three relatively telescoped shells, the innermost of which has a closure near the inlet head, the space between the inlet head and the closure forming an unrestricted expansion chamber into which the inlet opens, the innermost shell being connected to the next adjacent or intermediate shell by a plurality of transverse annular diaphragms forming longitudinally spaced chambers around the inner shell, the inner shell I having near its inlet end a plurality -of holes through which gases pass from the expansion chamber to the inside of the inner shell, the inner shell also having a substantial area covered with a plurality of perforations opening to the chambers, the inner shell also opening to the mediate shell, ythe intermediate shell also having utlet of the silencer, the intermediate shell havholes neer the outlet end intercommunicating ing a plurality of holes at the expansion chamthe spaces on opposite sides of the intermediate her fori, communicating the latter chamber with shell.

5 the space between the intermediate shell and the VIRGIL OLDBERG. 80

outer shell, there being annular chamber-form- 'WlLLIAM C. MORGAN, JR. ing means between the outer shell and the inter- 2o l t 95 

